With regard to such a BBW type vehicle brake device, an arrangement that includes a tandem type master cylinder, a tandem type slave cylinder, a wheel cylinder of a first line, and a wheel cylinder of a second line, connects a first fluid pressure chamber of the master cylinder to the wheel cylinder of the first line via a first fluid pressure chamber of the slave cylinder, connects a second fluid pressure chamber of the master cylinder to the wheel cylinder of the second line via a second fluid pressure chamber of the slave cylinder, operates the wheel cylinders of the first and second lines by means of a brake fluid pressure generated by the slave cylinder when the system is normal, and operates the wheel cylinders of the first and second lines by means of a brake fluid pressure generated by the master cylinder when there is an abnormality of the system is known from Patent Document 1 below.